OK, now that the Jitterbug EarBug has left my system (and probably entered yours, sorry), I can focus on good HT tactics. Sorry Tuomo, I like "HT" for Halftrack better than ht.
They're great for throwing Crew Smoke, zooming around the flanks and cutting rout paths, getting Encircling shots, and keeping brokies DM. Yes, in a pinch they're also great for VBM or TPBF Freezing enemy units, but as always, you need to be OK with losing the HT to a CCRF roll - they're Open Topped so they get a -2 DRM to the roll, so make sure you keep them in Motion to counterbalance that with a +2.
One thing I've rarely done with them is use them as mobile platforms for squads, but that's just because I haven't played the right scenarios. That lovely +2 CE DRM amounts to the Passengers getting the benefit of a Wooden Building that comes along wherever they go. Toss in an infantry or even armor leader to direct the fire and that's some Style Points right there. I'd be interested in hearing about scenarios that feature THIS, because it sounds like great fun.